Various devices are known in the art for performing high-precision measurements of workpieces using a handheld mechanism. For example, U.S. Pat. Nos. 1,132,704; 3,849,890; 4,485,556; 4,561,185; and 8,091,251 (referred to herein as the '704, '890, '556, '185, and '251 patents), each of which is hereby incorporated by reference in its entirety, disclose micrometer devices. In particular, modern micrometers such as that disclosed in U.S. Pat. No. 5,495,677 (the '677 patent), which is hereby incorporated by reference in its entirety, comprise a linear digital sensor for determining measurements, rather than relying on accurate micrometer threads in combination with a rotary position-sensing device. Using a linear digital sensor eliminates the need to use accurate or fine pitch threads in order to drive the micrometer.
Various electronic calipers are known that use electronic position encoders. These encoders are generally based on low-power inductive, capacitive, or magnetic position-sensing technology. In general, an encoder may comprise a readhead and a scale. The readhead may generally comprise a readhead sensor and readhead electronics. The readhead outputs signals that vary as a function of the position of the readhead sensor relative to the scale, along a measuring axis. In an electronic caliper, the scale is generally affixed to an elongated scale member that includes a first measuring jaw and the readhead is affixed to a slider that is movable along the scale member and that includes a second measuring jaw. Thus, measurements of the distance between the two measuring jaws may be determined based on the signals from the readhead. Exemplary electronic calipers are disclosed in commonly assigned U.S. Pat. Nos. RE37490; 5,574,381; and 5,973,494, each of which is hereby incorporated by reference in its entirety.
In the process of taking dimensional measurements using hand tools such as micrometers or calipers, it is necessary for a workpiece to be properly seated against two contact surfaces in order to provide a precise dimensional measurement. It has been conventional to rely solely upon the user to judge and/or determine that this condition is fulfilled. However, in many industrial inspection operations it would be desirable to determine that this condition is fulfilled by operations independent of and/or in addition to the user determination, especially for less skilled users.